In other species: dog , domestic cat

Possibly relevant human trait(s) and/or gene(s) (MIM number): 306900

Mendelian trait/disorder: unknown

Considered a defect: yes

Cross-species summary: Also called factor IX deficiency or Christmas disease. This is one of the two X-linked bleeding disorders, haemophilia A being the other. The fact that these two disorders are X-linked in all species reported to date provides strong support for Ohno's suggestion that the X chromosome has been highly conserved throughout evolution.